Detection and location of wireless field devices

ABSTRACT

A method of evaluating a potential location to add a wireless field device to an existing network of a plurality of existing wireless field devices is provided. The method includes placing a handheld field maintenance tool in the potential location and causing the handheld field maintenance tool to identify wireless field devices within communicative range of the potential location. Information related to wireless communication at the potential location is viewed. Methods are also provided for identifying a selected field device in a process installation using a handheld field maintenance tool.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on and claims the benefit of U.S.provisional patent application Ser. No. 61/178,757, filed May 15, 2009,the content of which is hereby incorporated by reference in itsentirety.

BACKGROUND

In industrial settings, control systems are used to monitor and controlindustrial and chemical processes, and the like. Typically, the processcontrol system performs these functions using field devices distributedat key locations in the industrial process and coupled to the controlcircuitry in the control room by a process control loop. Field devicesgenerally perform a function, such as sensing a parameter or operatingupon the process, in a distributed control or process monitoring system.

Some field devices include a transducer. A transducer is understood tomean either a device that generates an output signal based on a physicalinput or that generates a physical output based on an input signal.Typically, a transducer transforms an input into an output having adifferent form. Types of transducers include various analyticalequipment, pressure sensors, thermistors, thermocouples, strain gauges,flow transmitters, positioners, actuators, solenoids, indicator lights,and others.

Some process installations may involve highly volatile, or evenexplosive, environments. Accordingly, it is often beneficial, or evenrequired, for field devices and the handheld field maintenance toolsused with such field devices to comply with intrinsic safetyrequirements. These requirements help ensure that compliant electricaldevices will not generate a source of ignition even under faultconditions. One example of Intrinsic Safety requirements is set forthin: APPROVAL STANDARD INTRINSICALLY SAFE APPARATUS AND ASSOCIATEDAPPARATUS FOR USE IN CLASS I, II and III, DIVISION NUMBER 1 HAZARDOUS(CLASSIFIED) LOCATIONS, CLASS NUMBER 3610, promulgated by Factory MutualResearch October, 1998. Examples of handheld field maintenance toolsthat comply with intrinsic safety requirements include those sold undertrade designations Model 375 Field Communicator and Model 475 FieldCommunicator, available from Emerson Process Management of Austin, Tex.

Typically, each field device also includes communication circuitry thatis used for communicating with a process control room, or othercircuitry, over a process control loop. Traditionally, analog fielddevices have been connected to the control room by two-wire processcontrol current loops. In some installations, wireless technologies havebegun to be used to communicate with field devices. Wireless operationsimplifies field device wiring and set-up.

One wireless process communication technology standard is known as theWirelessHART standard. The WirelessHART standard was published by theHART Communication Foundation in September 2007. Relevant portions ofthe Wireless HART® Specification include: HCF_Spec 13, revision 7.0;HART Specification 65—Wireless Physical Layer Specification; HARTSpecification 75—TDMA Data Link Layer Specification (TDMA refers to TimeDivision Multiple Access); HART Specification 85—Network ManagementSpecification; HART Specification 155—Wireless Command Specification;and HART Specification 290—Wireless Devices Specification.

Another wireless network communication technology is set forth inISA100.11a. This technology proposes wireless communication at the 2.4GHz frequency using radio circuitry in accordance with IEEE802.15.4-2006. The ISA100.11 standard is maintained by the InternationalSociety of Automation (ISA).

While these wireless communication technologies provide importantadvantages to the art of process control and communication, traditionaltechniques for maintaining and configuring wireless field devices thatemploy such communication is sometimes rendered inefficient.

SUMMARY

A method of evaluating a potential location to add a wireless fielddevice to an existing network of a plurality of existing wireless fielddevices is provided. The method includes placing a handheld fieldmaintenance tool in the potential location and causing the handheldfield maintenance tool to identify wireless field devices withincommunicative range of the potential location. Information related towireless communication at the potential location is viewed. Methods arealso provided for identifying a selected field device in a processinstallation using a handheld field maintenance tool.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic view of a wireless process control environmentin which embodiments of the present invention are particularly useful.

FIG. 2 is a diagrammatic view of a wireless process control environmentin which a new wireless field device is being added.

FIG. 3 is a diagrammatic view of a wireless process control environmentin which a new wireless field device is being added in accordance withan embodiment of the present invention.

FIG. 4 is a flow diagram of a method of evaluating a potential locationfor a new wireless field device in accordance with an embodiment of thepresent invention.

FIG. 5 is a diagrammatic system block diagram of a handheld fieldmaintenance tool in accordance with the embodiment of the presentinvention.

FIG. 6 is a diagrammatic view of a method of locating a selected fielddevice using a handheld field maintenance tool in accordance with anembodiment of the present invention.

FIG. 7 is a flow diagram of a method of locating a selected field deviceusing a handheld field maintenance tool in accordance with an embodimentof the present invention.

FIG. 8 is a diagrammatic view of a method of locating a selected fielddevice in accordance with another embodiment of the present invention.

FIG. 9 is a flow diagram of a method of locating a selected field devicein accordance with another embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 is a diagrammatic view of a wireless process control environmentin which embodiments of the present invention are particularly useful.As illustrated in FIG. 1, a plurality of wireless field devices 10 arecommunicatively coupled either directly or indirectly via wirelesscommunication to wireless gateway 20. Wireless field devices 10 aregenerally illustrated as wireless process variable transmitters, such asthose sold under the trade designation Model 3051S wireless pressuretransmitter, from Emerson Process Management, of Chanhassen, Minn.However, those skilled in the art will recognize that wireless fielddevices 10 can include other types of wireless process variabletransmitters, as well as wireless actuators, valve positioners, etcetera. Wireless gateway 20 is configured to communicate with wirelessfield devices 10 using known wireless process communication protocols,such as the WirelessHART protocol described above. One example of awireless gateway is sold under the trade designation Model 1420 byEmerson Process Management, of Chanhassen, Minn. Wireless gateway 20includes one or more wired ports that are configured to couple to alocal area network, such as an Ethernet local area network asillustrated at reference numeral 22. By virtue of its wired connection,wireless gateway 20 can provide information to and receive informationfrom any device coupled to local network 22 such as workstations 24 and26.

The wireless field device network illustrated in FIG. 1 can beconsidered a mesh network in that some of the field devices communicatewith other field devices to pass their communication ultimately on towireless gateway 20. Thus, a field device that is located too far awayfrom wireless gateway 20 to otherwise communicate directly, can stillprovide wireless process communication by virtue of communicationthrough one or more other wireless field devices.

FIG. 2 is a diagrammatic view of a wireless process control environmentin which a new wireless field device is being added. When installationof a new wireless field device is required, the process is currentlyquite cumbersome. For wireless field devices, the physical position ofthe field device is often very important. This is because the physicalposition of the device will affect its proximity to other devices in themesh network as well as proximity to a gateway. Further, sources ofelectromagnetic interference or physical obstructions may affect a fielddevice more significantly at one position versus another. Thus, when auser is planning to install a new wireless field device into an existingnetwork of wireless field devices, the user will generally perform anumber of tasks and evaluations relative to the physical location of thenew device.

The user will typically evaluate physical distances between the proposedinstallation location illustrated at reference numeral 30 in FIG. 2 andother connections points 10 (which in a self-organizing network could beany member of the network) and decide if the distances are within theexpected effective communication range of the new wireless field device.

In order to study location 30 in detail, the user will often walk intothe field to location 30 and place a wireless test device at location30. Then, the user will return to one of workstations 24, 26 and accesswireless gateway 20 and wait for the wireless test device to join thewireless network. The wireless test device can require up to 10 minutesto join the network. Once the test device does join the network, theuser views communication characteristic information relative to the testdevice through a user interface provided by the wireless gateway. Ifproposed location 30 is satisfactory, the user then returns to location30 and replaces the test device with the new wireless field device.However, if position 30 is not satisfactory, the entire process isrepeated for an alternate location. If the user is exploring even a fewpotential locations, the process can quickly consume significant time.

FIG. 3 is a diagrammatic view of a wireless process control environmentin which a new wireless field device is being added in accordance withan embodiment of the present invention. The embodiment illustrated withrespect to FIG. 3 leverages a new ability of a handheld fieldmaintenance tool to improve the process of adding new wireless fielddevices to existing wireless networks. Instead of deploying a test fielddevice to proposed location 30, handheld field maintenance tool 52 isused. Tool 52 has a wireless process communication module (Shown in FIG.5) that allows tool 52 to listen to and communicate directly with fielddevices 10. Accordingly, when tool 52 is located at position 30, a usercan selected a function supplied by tool 52 to cause tool 52 to identifyall wireless field devices 10 within communication range of position 30.Tool 52 then displays the wireless field devices 10 within range ofposition 30. This display may simply include the number of field deviceswith which tool 52 can communicate at position 30. However, the displaycan be more sophisticated including a listing of device tags or MACaddresses, and the signal strength at position 30. Additionally, tool 52can also measure and report other connectivity issues, such as thepresence of electromagnetic interference, other process communicationnetworks, communication errors, or any other suitable parameter ofinterest to a technician deploying a new wireless field device. Theembodiment described with respect to FIG. 3 is believed to beparticularly applicable to WirelessHART, but any other suitable wirelessprocess communication protocol can be used. Moreover, while theembodiment described with respect to FIG. 3, is illustrated relative tohandheld field maintenance tool 52, any device that can communicate onthe wireless sensor network and provide useful information to atechnician or user may be employed. Thus, tool 52 could simply be amodule or device that plugs into a laptop computer or other suitablemobile device. However, since the device is located, at least some ofthe time, in the field, it is preferred that tool 52 comply with atleast one intrinsic safety specification, such as that listed above.

Additionally, or alternatively, the signal quality at position 30 can beevaluated over time. Thus, if position 30 is susceptible to periodicelectromagnetic interference, such a study would detect suchinterference thereby addressing a potentially intermittent communicationdifficulty. The study of position 30 can be done using a softwareapplication resident in one or more field devices 10, gateway 20, orpreferably tool 52 to continually or periodically monitor signalstrength of each network member over time. Preferably, the monitoredsignal strength information is stored and combined with geographicinformation (such as a map of the network) to provide a user with agraphical, intuitive depiction of signal quality as a function ofposition in the wireless process network. This map is termed a networkheat map and can be used to graphically depict past history of signalstrength to 1, 2, 3, 4 . . . et cetera devices in the area of position30. Further, the application, in some embodiments, illustrates thelowest signal strength to 1, 2, 3 . . . et cetera wireless fielddevices. Further still, in some embodiments, the software applicationcan recommend which wireless sensor network the new field device shouldjoin as well as provides an indication of anticipated communicationreliability for the new wireless field device.

FIG. 4 is a flow diagram of a method of evaluating a potential locationfor a new wireless field device in accordance with an embodiment of thepresent invention. Method 60 begins at block 62 where a handheld fieldmaintenance tool is placed at a proposed location of a new wirelessfield device. Next, at block 64, the handheld field maintenance toolidentifies at least some wireless field devices within range of thehandheld field maintenance tool. Preferably, the handheld fieldmaintenance tool identifies all wireless field devices within rangeduring block 64. At block 66, the handheld field maintenance toolprovides information related to the wireless communication to a user viaa display of the handheld field maintenance tool. This information maybe the number of field devices found; the device tags of the fielddevices; the signal strength relative to each field device, et cetera.

FIG. 5 is a diagrammatic system block diagram of a handheld fieldmaintenance tool in accordance with the embodiment of the presentinvention. It is preferred that tool 52 comply with at least oneintrinsic safety specification, such as that listed above, in order tohelp ensure safety in potentially explosive environments.

Handheld field maintenance tool 52 includes at least one wirelessprocess communication module 120. Suitable examples for wireless processcommunication module 120 include a module that generates and/or receivesproper signals in accordance with a known wireless communicationprotocol, such as the WirelessHART protocol described above. Anothersuitable wireless process communication protocol is that set forth inISA100.11a described above. While FIG. 5 shows a single wireless processcommunication module 120, it is expressly contemplated that any suitablenumber of wireless process communication modules can be used tocommunicate in accordance with various wireless process communicationprotocols now in existence or later developed.

Handheld field maintenance tool 52 also includes at least one secondarywireless communication protocol module 122. Wireless communicationprotocol module 122 can communicate in accordance with one or more ofthe options shown in phantom in FIG. 5. Specifically, wirelesscommunication protocol module 122 may communicate in accordance with aBluetooth specification 124; a Wi-Fi specification 126; a known RFIDspecification 128; cellular communication techniques 130; and/orsatellite communication 132. These communication techniques andmethodologies allow handheld field maintenance tool 52 to communicatedirectly with wireless gateway 20 either via direct wirelesscommunication, or using the Internet to which a wireless gateway isgenerally coupled. While one wireless communication protocol module 122is shown in FIG. 5, any suitable number may be used. Each of thewireless process communication protocol module 120 and wirelesscommunication protocol module 122 is coupled to controller 130 which isalso coupled to the wired process communication module 138. Controller130 is preferably a microprocessor that executes a sequence ofinstructions to perform handheld field maintenance tasks. Wired processcommunication module 138 allows the handheld field maintenance tool tobe physically coupled via a wired connection at terminals 142, 144 to afield device. Examples of suitable wired process communication includethe highway addressable remote transducer (HART®) protocol, theFOUNDATION™ Fieldbus protocol, and others.

Handheld field maintenance tool 52 can include a number of optionalitems that facilitate additional embodiments of the present invention.Specifically, tool 52 can include a position detection module, such asGPS module 150. GPS module 150 can be configured to additionally use theWide Area Augmentation System (WAAS) for improved accuracy and/or can beconfigured to operate using differential GPS techniques as appropriate.Module 150 is coupled to controller 130 to provide controller 130 withan indication of the geographic position of tool 52. Additionally, tool52 also preferably comprises compass module 152 coupled to controller130 such that tool 52 can indicate the direction in which it ispointing. Finally, tool 52 can also include tilt module 154 coupled tocontroller 130 to provide an indication to controller 130 relative to anangle of inclination of tool 52 relative to gravity. However, additionalaxes of sensing are also contemplated.

The optional components of tool 52 are particularly useful inembodiments of the present invention where a handheld field maintenancetool helps a technician or engineer find the physical location of awireless field device in the field. An oil refinery is often a verylarge process installation with many field devices positioned at variouslocations, some of which may not be readily visible. When a technicianor engineer needs to physically locate a field device to performengineering, setup and maintenance tasks, the technician or engineerwould previously need to perform one of the following tasks. Thetechnician or engineer would be forced to search for the field devicebased on memory or word-of-mouth directions. Alternatively, thetechnician or engineer would look up the field device in engineeringdrawings, which often do not contain detailed information about thephysical location of the device. Then, based on that often limitedinformation, the technician or engineer would attempt to physically findthe device in the plant or process installation.

FIG. 6 is a diagrammatic view of a process of finding a wireless fielddevice using a handheld field maintenance tool to locate a selectedfield device in accordance with an embodiment of the present invention.Handheld field maintenance tool 100 can be identical to tool 52described above with respect to FIG. 5. However, a different referencenumeral is used because it need not be the same. Tool 100 includes auser interface (in the form of a keypad, navigation buttons, and adisplay) that allows a technician or engineer to select a specific fielddevice to locate. Such selection will generally be in the form ofselecting a device tag or identifier, but may take any suitable form. Inthe example shown in FIG. 6, the technician has selected wireless fielddevice 206 among devices 200, 202, 204, and 206. While four fielddevices are illustrated, in reality, the field devices could number inthe hundreds with field devices dispersed throughout the factory orprocess installation. Preferably, handheld field maintenance tool 100contains a map of the process installation that is either pre-loadedinto the handheld field maintenance tool, or communicated wirelessly totool 100 through any suitable means. Additionally, in the event thathandheld field maintenance tool 100 has previously interacted with theselected field device (such as during installation of the field device)handheld field maintenance tool 100 may have acquired information thatrelates the position (as indicated by the GPS module at the time of theprevious interaction) to the device. This position information can bewritten to the field device, stored in handheld field maintenance tool100 or both. It is also contemplated that handheld field maintenancetool 100 or a different handheld field maintenance tool can access thewireless field device using any suitable wireless communication andreceive from the wireless field device location information indicativeof a position of the wireless field device. Once the device tag isidentified, the handheld field maintenance tool obtains positioninformation, preferably from GPS module 150 relative to the position oftool 100. Once tool 100 knows its own position, it generates anindication, vector, route, or other suitable directions to help thetechnician or engineer travel to the physical location of field device206. Preferably, the map includes an indication of tool 100 on the mapso the user can gauge progress to the destination (field device 206)Additionally, since the technician is usually walking, and GPS headinginformation is based on movement, tool 100 may use its optional compassto provide the user with a directional indication 208 that points orleads the technician or engineer to the selected field device 206 evenwhen the technician or engineer is standing still. Finally, since atleast some process installations such as refineries may have fielddevices positioned tens or hundreds of feet above the ground, tool 100can use tilt module 154 to cause the technician or engineer to inclinetool 100 at an angle that causes the tool to be essentially aimed atfield device 206. Thus, if a user reaches a position where field device206 is supposed to be, but field device 206 is actually located faroverhead, tool 100 would indicate an angle of incline that would directthe user's attention to the proper elevation to locate the field device.

FIG. 7 is a flow diagram of a method of locating a selected field deviceusing a handheld field maintenance tool in accordance with an embodimentof the present invention. Method 70 begins at block 72 where anindication of a physical location of a selected field device is obtainedby a handheld field maintenance tool. This may be done by accessing aninternal pre-loaded database within the handheld field maintenance toolthat correlates all device tags in the process installation to physicalpositions. Alternatively, the handheld field maintenance tool cangenerate a query based on the selected device identification to asuitable server or computing device in an asset management system toreceive position information relative to the selected device. As setforth above, since the handheld field maintenance tool has amplewireless communication abilities, this query may be submitted while theuser is in the field. Next, at block 74, the handheld field maintenancetool determines its current position. This can be done in any suitablemanner, but preferably includes accessing an internal GPS module, suchas module 150. Then, the controller of the handheld field maintenancetool processes the physical location of the selected field device andthe current position of the handheld field maintenance tool to providean indication to the user to direct the user toward the physicallocation of the selected wireless field device.

Another aid for the technician or engineer's search for the wirelessfield device is illustrated with respect to FIG. 8. Specifically, oncethe user has selected a field device to locate, the handheld fieldmaintenance tool 100 can communicate on the wireless sensor network inwhich the field device is located to cause the field device to generatea local annunciation to help capture the user's attention. This localannunciation 210 can be in the form of an audible alert or siren, aflashing light or indicator, or both. Thus, as the technician orengineer is walking near the field device, the field device's sounds andlights will help the technician or engineer focus on the desired fielddevice.

FIG. 9 is a flow diagram of a method of locating a selected field devicein accordance with another embodiment of the present invention. Method250 begins at block 252 where a user selects a wireless field devicewith a handheld field maintenance tool. Next, at block 254, the handheldfield maintenance tool generates suitable wireless communication,preferably wireless process communication, to cause the selected fielddevice to generate a local annunciation.

While each of the embodiments described with respect to FIGS. 6 and 8can be practiced separately, combinations of the embodiments are alsouseful. For example, the user can obtain and follow a map to arrive inthe general area of the selected field device. Then, once handheld fieldmaintenance tool senses proximity above a certain threshold to the fielddevice, the handheld field maintenance tool can automatically interactwith the field device through the wireless sensor network to cause thefield device to generate the local annunciation and confirm the locationof the field device. Further still, if the user reaches the location ofthe selected field device and cannot find it, the user may also obtainadditional location assistance information using the handheld fieldmaintenance tool. For example, the user may download an image of thefield device located in its position. The user can then view the imageand compare it to the user's physical reality to find the field device.

Although the present invention has been described with reference toparticular embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention.

What is claimed is:
 1. A method of locating and directing a user to aselected field device in a process installation with a handheld fieldmaintenance tool, the method comprising: detecting a physical locationof the selected field device via a wireless communication module of thehandheld field maintenance tool, wherein detecting the physical locationcomprises submitting a query to a server over a wireless connection,wherein the query comprises an identification of the selected fielddevice; detecting a current position of the handheld field maintenancetool, wherein detecting the current position of the handheld fieldmaintenance tool comprises accessing an internal GPS module of thehandheld field maintenance tool; generating, automatically, anindication, based at least in part on the detected physical location andat least in part on the detected current position, on the handheld fieldmaintenance tool that directs the user of the handheld field maintenancetool from the detected current position to the detected physicallocation of the selected field device; and automatically generating alocal annunciation at the selected field device when the currentposition is within a threshold proximity of the physical location of theselected field device.
 2. The method of claim 1, wherein generating anindication to the user includes presenting the user with a mapindicating the current position and the physical location of theselected field device.
 3. The method of claim 1, wherein the handheldfield maintenance tool complies with at least one intrinsic safetyspecification.
 4. The method of claim 1, wherein the indication includesa heading.
 5. A method of locating and directing a user to a selectedfield device in a process installation with a handheld field maintenancetool, the method comprising: detecting a physical location of theselected field device via a wireless communication module of thehandheld field maintenance tool, wherein detecting the physical locationcomprises submitting a query to a server over a wireless connection,wherein the query comprises an identification of the selected fielddevice; detecting a current position of the handheld field maintenancetool, wherein detecting the current position of the handheld fieldmaintenance tool comprises accessing an internal GPS module of thehandheld field maintenance tool; generating, automatically, anindication, based at least in part on the detected physical location andat least in part on the detected current position, on the handheld fieldmaintenance tool that directs the user of the handheld field maintenancetool from the detected current position to detected physical location ofthe selected field device; and wherein the indication includes anelevation angle.